const fsm = wx.getFileSystemManager();
 const FILE_BASE_NAME = 'tmp_base64src'; //自定义文件名
  
 function base64src(base64data, cb) {
   const [, format, bodyData] = /data:image\/(\w+);base64,(.*)/.exec(base64data) || [];
   if (!format) {
     return (new Error('ERROR_BASE64SRC_PARSE'));
   }
   const filePath = `${wx.env.USER_DATA_PATH}/${FILE_BASE_NAME}.${format}`;
   const buffer = wx.base64ToArrayBuffer(bodyData);
   fsm.writeFile({
     filePath,
     data: buffer,
     encoding: 'binary',
     success() {
       cb(filePath);
     },
     fail() {
       return (new Error('ERROR_BASE64SRC_WRITE'));
     },
   });
 };
 module.exports = base64src;